Consistent naming of "count" fields

[kainino0x]

Spin off from #155

Most count fields are worded as singular+"Count", like bindGroupLayoutCount. The following are plural+"Count:

pipelineStatisticsCount // should be pipelineStatisticCount?
colorFormatsCount // should be colorFormatCount?
requiredFeaturesCount // should be requiredFeatureCount?
bundlesCount // should be bundleCount?

[kainino0x]

webgpu.h meeting:
Agreed on singular+"Count" (even for pipelineStatisticCount which is slightly odd but fine if you think about it)